docs: def Serghides_2(Re, eD):
      r'''Calculates Darcy friction factor using the method in Serghides (1984)
      [2]_ as shown in [1]_.
  
      .. math::
          f_d = \left[ 4.781 - \frac{(A - 4.781)^2}
          {B-2A+4.781}\right]^{-2}
  
      .. math::
          A=-2\log_{10}\left[\frac{\epsilon/D}{3.7}+\frac{12}{Re}\right]
  
      .. math::
          B=-2\log_{10}\left[\frac{\epsilon/D}{3.7}+\frac{2.51A}{Re}\right]
  
  
      Parameters
      ----------
      Re : float
          Reynolds number, [-]
      eD : float
          Relative roughness, [-]
  
      Returns
      -------
      fd : float
          Darcy friction factor [-]
  
      Notes
      -----
      No range of validity specified for this equation.
  
      Examples
      --------
      >>> Serghides_2(1E5, 1E-4)
      0.018486377560664482
  
      References
      ----------
      .. [1] Winning, H. and T. Coole. "Explicit Friction Factor Accuracy and
         Computational Efficiency for Turbulent Flow in Pipes." Flow, Turbulence
         and Combustion 90, no. 1 (January 1, 2013): 1-27.
         doi:10.1007/s10494-012-9419-7
      .. [2]	Serghides T.K (1984)."Estimate friction factor accurately"
         Chemical Engineering, Vol. 91(5), pp. 63-64.
      '''
      A = -2*log10(eD/3.7 + 12/Re)
      B = -2*log10(eD/3.7 + 2.51*A/Re)
      return (4.781 - (A - 4.781)**2/(B - 2*A + 4.781))**-2